Every year it's the same old story. The sun is shining, the weather is nice and guess what!? You're not allowed to swim in Kralingse Plas. Why? Because blue-green algae has taken over the lake. This year, Rotterdam is taking preventive measures.

What is blue-green algae?

Blue-green algae, or blauwalg in Dutch, is a bacteria that causes nausea and rash. In previous years, measures weren't deemed necessary until the amount of algae in the water actually became a health hazard. This time, Rotterdam is trying to get ahead of the problem, increasing the likelihood of there not being any incidents all summer long.

What's the plan?

One way of fighting this bacteria is by adding very low concentrations of hydrogen peroxide in the water. We're talking about concentrations 10,000 times lower than the mouthwash you can buy at the drugstore. From July 4th through July 8th, the beach will be cordoned off and a special boat will release the hydrogen peroxide solution into the water. You will not be allowed to swim on those days and sailing should be kept to a minimum.